The present invention relates generally to battery chargers, and more specifically to a battery charger for charging the battery of a vehicle-mounted equipment with a current supplied from the vehicle battery.
With known battery chargers, the rechargeable battery of a vehicle-mounted equipment is charged with a current supplied from the automobile battery. Regardless of the voltage of the automobile battery, charging operation automatically starts when the voltage of the equipment's battery reduces to a predetermined level and terminates when the voltage rises above a specified level or a specified time interval has elapsed. Therefore, the automobile battery is often forced to discharge under low voltage conditions, causing an irrecoverable damage thereon.